1. Field of the Invention
The present invention relates to a disk for ascertaining symbol positions on a reel of a slot machine, to a displayed symbol identifier of a mechanical slot machine, and to a mechanical slot machine.
2. Background Information
In the past, there have been proposals for a slot machine in which symbols displayed in a symbol display region are identified with an optical sensor by giving a distinctive shape to a disk that shares its rotational axis with a reel (see, for example, U.S. Pat. No. 6,043,483).
The apparatus in U.S. Pat. No. 6,043,483 is configured such that there is a disk having a plurality of square notches around its edge, as on a gear, and when this disk rotates, the edge of the disk passes between the light source side of the optical sensor and the reading side, which is across from this light source. When the disk is rotated, light blocking portions that block the light around the edge of the disk, and light transmitting portions that have square notches and transmit light, alternately pass through the optical sensor. The disk is provided with light blocking portions that vary in size in the peripheral direction at a reference location, and the symbol being displayed is identified from the number of passes made by the light blocking portions or light transmitting portions.
There has also been proposals in the past for a reel mechanism that detects the stopping position and the like from the layout of holes made in a disk (see, for example, European Patent Application Publication No. 0023136).
The reel mechanism in European Patent Application Publication No. 0023136 comprises a disk provided with two rows of a plurality of holes in the peripheral direction, and information encoded by the holes is read from the light passing through the holes as the reel rotates.
As in U.S. Pat. No. 6,043,483, there has been a proposal for an apparatus in which a disk is arranged on a rotary shaft, and the symbol displayed in the symbol display region of a slot machine is identified by means of the amount of rotation from a reference position on this disk, out of all the symbols on a reel that has the same rotational axis.
However, with an apparatus such as this, because the symbol currently being displayed is identified from the amount of rotation from a reference position, the disk must have a portion that serves as the reference position, and to detect the rotational position of the disk, this portion must pass through the detector. Therefore, immediately after the power is turned on, the symbol currently being displayed cannot be identified unless the disk is first rotated so that the reference position passes the position of the sensor.
In addition, if the symbol actually being displayed should deviate from the symbol display region due to vibration of the housing, malfunction, or the like, it cannot be detected unless the disk is rotated so that the portion serving as the reference position passes the sensor.